The present invention relates to a coupling device, more particularly of the quick-connect type, arranged to enable one end of a duct to be connected to an element of a fluid transport circuit, which element may be an element that emits or receives fluid, and in particular a pipe, a manifold, a member for regulating flow rate or pressure, an actuator, a tank, a pump, or the like.
Such a coupling device is shown in FIG. 6 and generally comprises a tubular body 1 defining a channel 2 including a segment 3 for receiving a pipe end 100 (FIG. 3). In succession in a direction for inserting the pipe end 100 in the reception segment 3, the reception segment comprises: a locking member 4 for locking the pipe end 100 in the reception segment 3; a sealing member 5 for fitting tightly around an outside surface of the pipe end; a guide surface 6 for guiding the pipe end in the reception segment; and an abutment 7 for stopping the pipe end being pushed into the reception segment. By way of example, the locking member 5 is a clamp, as shown in FIG. 6, comprising a sleeve having one end subdivided into arms that are elastically deformable between a state for releasing the pipe end and a state for locking the pipe end. The clamp is movable axially in the reception segment between a pushed-in, release position in which the arms are in their release state, and a pulled-back locking position in which a surface of the body holds the arms in their state for locking the pipe end. The locking member 4 may also be a washer having an inside circumference subdivided into a plurality of teeth, the washer being deformable between a pipe-end passing state and a pipe-end locking state.
It is known that reversing of the pipe end as a result of traction being applied to the pipe end 100, or as a result of the circuit being pressurized, gives rise to a space (zone A in FIG. 6) between the terminal face of the pipe end 100 and the abutment 7. This space is larger with locking members of the clamp type than with those of the toothed washer type.
It is also known that the fluid tends to stagnate in this space, which constitutes a fluid retention zone. Such a retention zone is more particularly harmful when the fluid being transported is a perishable liquid that might deteriorate in the retention zone and pollute the liquid flowing in the circuit. Other pollutants, such as dirt, may also stagnate in the retention zone.
In order to remedy that drawback, proposals have been made for coupling devices in which the coupling is no longer sealed by the outside surface of the pipe end but via the terminal face thereof. In those coupling devices, the resilience of the sealing member compensates for the reversal of the pipe end, thereby preventing a retention zone being formed. Those coupling devices present the drawback that the abutment of the pipe end is not firm, such that an operator is not certain to have compressed the sealing member sufficiently to guarantee that the coupling remains sealed after reversal of the tube, or indeed that the coupling remains connected.
In fluid installations in which the quality of the fluid is monitored, provision is also made to clean the circuit regularly by causing a cleaning liquid to flow therein.
It is also known from document U.S. Pat. No. 4,643,466 a coupling device without any guiding surface for the pipe. In said coupling device, a ring is mounted in the channel in order to center the pipe in the device. Such a centering is different from a guiding which maintains a segment of the pipe along an axial direction of the channel.